1. Field of the Invention
The present invention relates to a thermal line head and an ink transfer printer using the same, in which an ink drop or ink drops selectively appear in accordance with a digital image-pixel signal, thereby producing an ink dot on a recording sheet of paper.
2. Description of the Related Art
Conventionally, a thermal line head, incorporated into a thermal printer, comprises an elongated rectangular ceramic base plate, a plurality of electric resistance elements or electric heater elements linearly aligned on the base plate, and plural pairs of lead wire elements, arranged on the base plate, which are electrically contacted with and joined to the electric heater elements, respectively. One of the lead wire elements in each pair is electrically connected to a driver circuit of a thermal head controller, and the other lead wire element is electrically grounded. The heater elements are selectively and electrically energized by the driver circuit, in accordance with a series of digital image-pixel signals, in a well-known manner.
With this conventional arrangement of the thermal line head, the electrical energization of the electric heater elements cannot be efficiently performed, because contact resistance is exhibited at connections between each of the electric heater elements and the pair of lead wire elements associated therewith. Namely, the electrical energy, to be applied to an electric heater element, is inefficiently used due to the existence of the contact resistance between the electric heater element concerned and the pair of lead wire elements associated therewith.
Therefore, an object of the present invention is to provide a thermal line head including a plurality of electric resistance elements or electric heater elements selectively and electrically energized in accordance with a series of digital image-pixel signals, wherein the energization of the electric heater elements can be efficiently performed.
Another object of the present invention is to provide a novel ink transfer printer which can advantageously use the aforesaid thermal line head.
Yet another object of the present invention is provide various types of thermal line heads and various types of novel ink transfer printers advantageously using these types of thermal line head.
In accordance with a first aspect of the present invention, there is provided a thermal line head comprising: an electrically-insulated base member; and a monolithic electrically-conductive pattern formed on a surface of the base member. The monolithic electrically-conductive pattern includes a plurality of first electrode sections, a plurality of second electrode sections and a plurality of constrictions, each of the plurality of constrictions extending between one of the plurality of first electrode sections and a corresponding one of the plurality of second electrode sections. The a cross-sectional area of the plurality of constrictions is smaller than that of the plurality of first and second electrode sections, whereby each of the plurality of constrictions serves as an electric resistance element.
The monolithic electrically-conductive pattern may be formed as a metal layer. Optionally, the monolithic electrically-conductive pattern may be formed as an electrically-conductive layer composed of an electrically-conductive coating material. Also, the monolithic electrically-conductive pattern further may include a grounded common terminal section electrically connected to the second plurality of electrode sections.
In the first aspect of the present invention, the thermal line head may further comprise an integrated driver circuit pattern formed on the surface of the base member, the integrated driver circuit pattern being electrically connected to the plurality of first electrode sections of the monolithic electrically-conductive pattern, such that the electric resistance elements are selectively and electrically energized in accordance with a series of digital image-pixel signals. If necessary, the electric resistance elements is at least covered with a protective layer, which a thermal resistance layer interposed between the electric resistance elements and the surface of the base member.
In accordance with the first aspect of the present invention, there is also provided an ink transfer printer, having the aforesaid thermal line head according to this first aspect, comprising: a frame member, having an opening, securely provided on the thermal line head such that the electric resistance elements are encompassed by the opening of the frame member; and a sheet of film that covers the frame member such that the opening of the frame member is defined as an ink space that stores ink, the film sheet including a plurality of fine pores arranged along an alignment of the electric resistance elements, at least one of the plurality of fine pores being allocated to and associated with each of the electric resistance elements. When each of the electric resistance elements is electrically energized to thereby generate thermal energy, an ink drop is formed on the film sheet from a corresponding pore thereof, due to the generation of the thermal energy.
Preferably, the film sheet is positioned with respect to the frame member such that each of the plurality of the pores is placed just above the corresponding one of the plurality of electric resistance elements.
In the first aspect of the present invention, the ink transfer printer may further comprise an ink reservoir provided on the thermal line head, the ink reservoir communicating with the ink space via a passage formed in the frame member, whereby the ink space is fed with ink from the ink reservoir.
In accordance with a second aspect of the present invention, there is provided a thermal line head comprising: an electrically-insulated base member; plural sets of at least two electric resistance elements formed on a surface of the base member and aligned with each other; and a driver circuit that selectively and electrically energizes the at least two electric resistance elements in each set in accordance with an associated digital image-pixel signal and an associated digital gradation-signal. When the digital image-pixel signal has a value xe2x80x9c0xe2x80x9d, none of the at least two electric resistance elements in a corresponding set are electrically energized. When the digital image-pixel signal has a value xe2x80x9c1xe2x80x9d, the selective and electrical energization of the at least two electric resistance elements in the corresponding set are performed in accordance with values of the digital gradation-signal, whereby a total thermal energy output of each of the plural sets of at least two electric resistance elements is stepwisely adjustable.
In the second aspect of the present invention, the driver circuit may be provided on the surface of the base member. Also, the at least two electric resistance elements in each set may have identical resistance values or different resistance values.
Preferably, one set of the plural sets of at least two electric resistance elements contains four electric resistance elements, two of the four electric resistance elements having first identical resistance values, a remaining two of the four electric resistance elements having second identical resistance values different from the first identical resistance values.
In accordance with the second aspect of the present invention, there is also provided an ink transfer printer, having the aforesaid thermal line head according to this second aspect, comprising: a frame member, having an opening, securely provided on the thermal line head such that the plural sets of at least two electric resistance elements are encompassed by the opening of the frame member; and a sheet of film that covers the frame member such that the opening of the frame member is defined as an ink space filled with ink, the film sheet including a plurality of fine pores arranged along an alignment of the plural sets of at least two electric resistance elements, at least one of the plurality of fine pores being allocated to and associated with each of the plural sets of at least two electric resistance elements. When the electric resistance elements in each set are selectively and electrically energized to generate thermal energy, an ink drop is formed on the film sheet from one of the plurality of fine pores corresponding to the generation of the thermal energy, with a size of the ink drop being stepwisely varied in accordance with a value of the digital gradation-signal.
In the second aspect of the present invention, the ink transfer printer may further comprise an ink reservoir provided on the thermal line head, the ink reservoir communicating with the ink space via a passage formed in the frame member, whereby the ink space is fed with ink from the ink reservoir.
In accordance with a third aspect of the present invention, there is provided a thermal line head comprising: an electrically-insulated base member; a plurality of electric resistance elements linearly formed on a surface of the base member; and an electrically-conductive wiring pattern arrangement formed on the surface of the base member, the electrically-conductive wiring pattern arrangement electrically activating the plurality of electric resistance elements. The electrically-conductive wiring pattern arrangement is constituted such that each of the electric resistance elements is surrounded by at least two pattern elements included in the electrically-conductive wiring pattern arrangement.
The electrically-conductive wiring pattern arrangement may include plural sets of first and second electrode patterns elements disposed so as to partially surround and electrically contact a corresponding one of the plurality of electric resistance elements. In this case, preferably, each of the first electrode pattern elements is formed as an L-shaped electrode pattern element, and each of the second electrode pattern elements is formed as a rectangular pattern element, the L-shaped electrode pattern element and the rectangular pattern element in each set act in conjunction with each other to surround the corresponding one of the plurality of electric resistance elements.
The electrically-conductive wiring pattern arrangement may further include a grounded common terminal pattern element electrically connected to the second electrode elements. In this case, preferably, the grounded common terminal pattern element contributes to surround the corresponding one of the plurality of electric resistance elements.
Optionally, the electrically-conductive wiring pattern arrangement includes a plurality of electrode pattern elements electrically connected to the plurality of electric resistance elements, and a grounded common terminal pattern element electrically connected to the plurality of electric resistance elements, such that two consecutive electrode pattern elements in conjunction with the grounded common terminal pattern element surround a corresponding one of the plurality of electric resistance elements. In this case, preferably, each of the electrode pattern elements is formed as an L-shaped electrode pattern element, and two consecutive L-shaped electrode pattern elements act in conjunction with each other to surround the corresponding one of the plurality of electric resistance elements.
In accordance with the third aspect of the present invention, there is also provided an ink transfer printer, having the aforesaid thermal line head according to this third aspect, comprising: a frame member, having an opening, securely provided on the thermal line head such that the plurality of electric resistance elements are encompassed by the opening of the frame member; and a sheet of film that covers the frame member such that the opening of the frame member is defined as an ink space that stores ink, the film sheet including a plurality of fine pores arranged along an alignment of the plurality of electric resistance elements, at least one of the plurality of fine pores being allocated to and associated with each of the plurality of electric resistance elements. When each of the electric resistance elements is electrically energized to generate thermal energy, an ink drop is formed on the film sheet from one of the plurality of fine pore corresponding to the generation of the thermal energy, with the thermal energy being efficiently localized in the vicinity of the heated resistance element, due to the surrounding of each of the electric resistance elements by the pattern elements included in the electrically-conductive wiring pattern arrangement.
In the third aspect of the present invention, the ink transfer printer may further comprise an ink reservoir provided on the thermal line head, the ink reservoir communicating with the ink space via a passage formed in the frame member, whereby the ink space is fed with ink from the ink reservoir.
In accordance with a fourth aspect of the present invention, there is provided an ink transfer printer comprising: an electrically-insulated base member; an electrically-conductive wiring pattern arrangement provided on a surface of the base member, the electrically-conductive wiring pattern arrangement including linearly-aligned plural sets of first and second electrode pattern elements, plural sets of first and second electric resistance elements that are linearly aligned on the electrically-conductive wiring pattern arrangement such that the first and second electric resistance elements in each set are electrically connected to a corresponding one set of the first and second electrode pattern elements; and a sheet of film provided on the surface of the base member so as to cover the electrically-conductive wiring pattern arrangement and the plural sets of first and second electric resistance elements to thereby define an ink space, that stores ink, between the sheet film and the surface of the base plate, the film sheet having a plurality of fine pores arranged along the alignment of the plural sets of first and second electric resistance elements, at least one of the plurality of fine pores being positioned between the first and second electric resistance elements in each set. The plural sets of first and second electric, resistance elements are securely pre-attached to an inner surface of the film sheet. When the first and second electric resistance elements in each set are electrically energized to thereby generate thermal energy, an ink drop is formed on the film sheet from one of the plurality of fine pores corresponding the generation of the thermal energy.
In this ink transfer printer, the plural sets of first and second electrode pattern elements, together with the plural sets of first and second electric resistance elements, may be securely pre-attached to the inner surface of the film sheet.
Optionally, the electrically-conductive wiring pattern arrangement may further include a grounded common terminal pattern element provided on the surface of the base member so as to be electrically connected to the first and second electric resistance elements in each set. In this case, preferably, the grounded common terminal pattern element, together with the plural sets of first and second electric resistance elements, is securely pre-attached to the inner surface of the film sheet.
Optionally, the electrically-conductive wiring pattern arrangement may further include a driver circuit device provided on the surface of the base member such that the electrical energization of one of the plural sets of first and second electric resistance elements is selectively performed through the corresponding one set of the first and second electrode pattern elements in accordance with a digital image-pixel signal. In this case, preferably, the driver circuit device, together with the plural sets of first and second electric resistance elements, is securely pre-attached to the inner surface of the film sheet.
In the fourth aspect of the present invention, the ink transfer printer may further comprise an ink reservoir provided on the surface of the base member, the ink reservoir having a spout portion, to which a side of the film sheet is adhered and sealed, whereby the ink reservoir is in communication with the ink space such that the ink space is fed with ink from the ink reservoir.
In accordance with the fourth aspect of the present invention, there is further provided another type of ink transfer printer comprising: an electrically-insulated base member; an electrically-conductive wiring pattern arrangement provided on a surface of the base member, the electrical conductive wiring pattern arrangement including a plurality of linearly aligned electrode pattern elements, a plurality of electric resistance elements provided and aligned on the electrical conductive wiring pattern arrangement such that the respective electric resistance elements are electrically connected to the electrode pattern elements; and a sheet of film provided on the surface of the base member so as to cover the electrical conductive wiring pattern arrangement and the electric resistance elements to thereby define an ink space, that stores ink, between the sheet film and the surface of the base plate, the film sheet being formed with a fine groove extending along the alignment of the plurality of electric resistance elements, and having a plurality of fine pores which are formed in and arranged along the alignment of the plurality of electric resistance elements, at least one of the plurality of fine pores being allocated to and associated with each of the plurality of electric resistance elements. The electric resistance elements are securely pre-attached to an inner surface of the film sheet. When each of the plurality of electric resistance elements is electrically energized to generate thermal energy, an ink drop is formed on the film sheet from one of the plurality of fine pores corresponding to the generation of the thermal energy.
In this other type of ink transfer printer according to the fourth aspect of the present invention, the plurality of electrode pattern elements, together with the plurality of electric resistance elements, may be securely pre-attached to the inner surface of the film sheet.
Optionally, the electrically-conductive wiring pattern arrangement may further include a grounded common terminal pattern element provided on the surface of the base member so as to be electrically connected to the plurality of electric resistance elements. In this case, preferably, the grounded common terminal pattern element, together with the plurality of electric resistance elements, is securely pre-attached to the inner surface of the film sheet.
Optionally, the electrically-conductive wiring pattern arrangement may further include a driver circuit device provided on the surface of the base member such that the electrical energization of each of the plurality of electric resistance elements is selectively performed through a corresponding one of the plurality of electrode pattern elements, in accordance with a digital image-pixel signal. In this case, preferably, the driver circuit device, together with the plurality of electric resistance elements, is securely pre-attached to the inner surface of the film sheet.
In this other type of ink transfer printer according to the forth aspect of the present invention, the ink transfer may further comprise an ink reservoir provided on the surface of the base member, the ink reservoir having a spout portion, to which a side of the film sheet is adhered and sealed, whereby the ink reservoir communicates with the ink space such that the ink space is fed with ink from the ink reservoir.
In accordance with a fifth aspect of the present invention, there is provided an ink transfer printer comprising: an electrically-insulated base member; a plurality of electric resistance elements linearly formed on a surface of the base member; a frame member, having an opening, securely provided on the surface of the base member such that the plurality of electric resistance elements are encompassed by the opening of the frame member; a sheet of film, having a linear perimeter side, adhered and sealed to the frame member, except for the linear perimeter side, such that the opening of the frame member is defined as an ink space that stores ink, the linear perimeter side of the film sheet extending along the linear formation of the plurality of electric resistance elements, and contacting a surface of the frame member; and a platen roller rotatably provided above and in contact with the film sheet such that a rotational axis of the platen roller is in parallel with the linear formation of the plurality of electric resistance elements, the linear perimeter side of the film sheet being pressed against the surface of the frame member so as to form a closed slit therebetween. When each of the electric resistance elements is electrically energized to generate thermal energy, a part of the ink penetrates the closed slit, due to the generation of the thermal energy, and then exits the closed slit as a fine ink drop.
In the fifth aspect of the present invention, the ink transfer printer may further comprise an ink reservoir provided on the surface of the base member, the ink reservoir communicating with the ink space via a passage formed in the frame member, whereby the ink space is fed with ink from the ink reservoir.
In accordance with the fifth aspect of the present invention, there is further provided another type of ink transfer printer an ink transfer printer comprising: an electrically-insulated base member;
a plurality of electric resistance elements linearly formed on a surface of the base member; a spacer member securely provided on the surface of the base member along the linear formation of the plurality of electric resistance elements; a sheet of film, having a linear perimeter side, adhered and sealed to the spacer member and the surface of the base member, except for the linear perimeter side, such that an ink space, that stores ink, is defined so as to include the linear formation of the plurality of electric resistance elements, the linear perimeter side of the film sheet extending along the linear formation of the plurality of electric resistance elements, and contacting the surface of the base member; and a platen roller that is rotatably provided above and in contact with the film sheet such that a rotational axis of the platen roller is in parallel with the linear formation of the plurality of electric resistance elements, the linear perimeter side of the film sheet being pressed against the surface of the base member so as to form a closed slit therebetween. When each of the plurality electric resistance elements is electrically energized to thereby generate thermal energy, a part of the ink penetrates the closed slit, due to the generation of the thermal energy, and then exits the closed slit as a fine ink drop.
In this other type of ink transfer printer according to the fifth aspect of the present invention, the ink transfer printer may further comprise an ink reservoir provided on the surface of the base member, the ink reservoir communicating with the ink space via a passage formed in the spacer member, whereby the ink space is fed with ink from the ink reservoir.
In each of the aforesaid aspects of the present invention, preferably, the film sheet is formed of a suitable synthetic resin material, such as polytetrafluoroethylene, exhibiting at least a moderate elasticity, a wear-resistant property and a thermal-resistant property.